SPH0645LM4H-B i2s microphone sensitivity measurements on ROBAT 226.238:¶
This report is used to calibrate the sensitivity of the SPH0645 I2S microphone array using a GRAS reference microphone. The calibration is done by playing back a series of chirp sweeps and measuring the response of both microphones. The sensitivity is calculated in terms of dB SPL (Sound Pressure Level) relative to 20 μPa.
Data for the experiments have been collected on May 9th, 2025, along with the measurements used to calculate the array directivity.
ROBAT 226.238:
- 5 mic array adafruit 5 i2s SPH0645LM4H-B from Knowles (https://cdn-shop.adafruit.com/product-files/3421/i2S+Datasheet.PDF), mounted on a custom PCB from Adafruit (https://www.adafruit.com/product/3421#description)
- 48khz recording from the array mics
- 192 KHz recordings from the GRAS reference mic (GRAS 40BF + 26AC preamplifier)
- 1.5 meters distance (~ far field = 10𝛌; 𝛌max = fmin; 343/2 = 171 Hz --> 10𝛌 = 1715 Hz; at 1000Hz: 4.5𝛌 = 4.5*0.343 = 1.5435 m)
HW settings:
- Harman kandon AWR 445 vol = -40 db
- fireface analog out 1/2 stereo vol = 0 db
- tweeter #1
- Ref mic: gras +30 db fireface channel 9, +20db channel A power module
WARNING This code is mostly derived from the code:
example_w-deconvolution_runthrough.py
at this link: https://github.com/activesensingcollectives/calibrate-mic/blob/master/example_w-deconvolution_runthrough.py and makes use of:
utilities.py
both developed by Thejasvi Beleyur.
Created on June 5 2025
@author: Alberto Doimo
In [1]:
from IPython.display import Image
from IPython.display import display
display(
Image(filename="./PXL_20250509_10061094.jpg", width=400),
Image(filename="./PXL_20250509_10062195.jpg", width=400),
Image(filename="./rme802_matrix.png", width=800),
Image(filename="./rme802_mixer.png", width=800)
)